Repeater Controller Board and Firmware (October 27, 2026)
This page introduces the board and firmware for an ESP32-S3-based FM repeater controller. Download the schematics, PCB design files, KiCad library, and firmware below. The sections below show the peripheral circuits, PCB fabrication, and board assembly.
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Bare PCB
Fully assembled board
Complete unit
Sales Information
Bare PCB
US$20.00
Partially assembled board for integration (without LCD panel)
US$70.00
Fully assembled board
US$80.00
Complete unit
US$126.67
For shipping costs, please contact us at the email address below. du9@ji1fgx.com
ESP32-S3 and Peripheral Circuit Schematics
ESP32-S3
Controller microcontroller
ILI9341
2.4-inch LCD with touch panel
DFPlayer
MP3 player used for voice ID announcements
DS3231
Real-time clock (RTC): TEFUK Essential DS3231 RTC Time Module
Analog Audio Mixer Circuit
This circuit combines receiver audio, CW tones generated by the ESP32-S3, and voice ID audio from the DFPlayer, and feeds the combined signal to the transmitter microphone input.
Receiver audio is coupled through a 600-ohm to 600-ohm audio transformer. The receiver audio, CW tone, and voice ID levels can each be adjusted using their respective potentiometers.
A portion of the receiver audio is also routed through level adjustment and protection circuitry to the audio input used for software DTMF decoding.
PCB designed in KiCad
PCB manufactured by JLCPCB
Assembled board
The analog audio mixer is on the left, the ESP32-S3 is on the right, and the RTC and DFPlayer are at the bottom.
VOX (voice-operated transmit control) was initially implemented using an op-amp circuit.
Because the circuit frequently triggered incorrectly, VOX was changed to a software implementation.
DTMF (touch-tone) decoding is also performed in software.
Board Adjustments, Connectors, and Main Components
Reference
Description / Function
VR1
Main rig AF volume
VR2
CW TONE
VR3
AF input level to the radio
VR4
Voice ID level
VR5
VOX / DTMF input level
J1
RTC (DS3231) connector
J2
SQL input from the radio
J3
+3 V power connector (unused)
J4
AF input from the radio
J5
MIC / PTT connections to the radio
J6
TX / RX LED connector
J7
LCD panel connector
U1 / U2
PC817 optocouplers
U3
ESP32-S3
U4
DFPlayer
Board Modification for Repeater Controller Ver0.3
The Ver0.3 board requires one jumper wire.
Connect a jumper wire from the cathode of diode D3 to pin 1 of the RTC connector J1.
This issue has been corrected in the Repeater Controller Ver0.4 board.